Method of making a molded conduit



T. E. MURRAY.

METHOD OF MAKING AMOLDED CONDUIT. APPLICATION FlLED JAN-6.1921.

1,38?,06? a Patented Aug. 1921.,

UNHED STATES METHOD OF MAKING A MOLDED CONDUIT.

Application filed January 6, 1921.

To all whom it may concern:

Be it known that I, THOMAS E. MURRAY, a citizen of the United States, residing at Brooklyn, in the county of Kings and State of,New York, have invented a certain new and useful Improvement in Methods of Making a Molded Conduit, of which the following is a specification.

Conduits of cement or like plastic material have been molded upon a spiral core of wire or the like provided with a cover or wrapping of paper or similar flexible material. When the core is withdrawn after the cement has hardened, the paper is left in the bore. Where the conduit is used to convey water or other liquid, the paper is softened and eventually detached, and thus becomes washed into elbows, valves or smaller branch pipes-in all cases more or less choking these and so stopping or impairing the flow.

My present invention is a method of molding said conduits so that the paper cover becomes a lining permanently affixed to the surface of the bore and which cannot be loosened or washed away, thus avoiding the abovedescribed difliculty. My said method consists in the steps performed in the order stated more particularly in the claim.

In the accompanying drawing- Figure 1 represents in'longitudinal section a portion of the conduit and core there in. Fig. 2 is a similar view of said conduit after the removal of the core.

Similar numbers of reference indicate like parts.

In performing my method, I first make a spiral core 1 of wire or strip metal. Upon said core I apply, preferablyby wrapping,

Specification of Letters Patent.

Patented Aug. 9, 1921.

Serial No. 435,408.

a cover 2 of paper or similar flexible sheet material. To this cover I next apply a coating 3 of pitch or other viscid adhesive material which will h'arden. While the pitch coating is still viscid, I apply thereto plastic cement or concrete 4 to form the conduit body, and allow said plastic material to become hard. Finally, I withdraw the core l. The cover 2 remains firmly held by the pitch coating and said coating in turn uniteswith the cement surrounding it, so that the cement, the cover and the pitch form a solid hard mass, of which the coverforms a fixed lining having a smooth inner surface, and which is not washed away nor loosened by liquid flow in the conduit. The said mass, besides, is wholly of insulating material,

thus adapting the conduit to the conveyance of electrical conductors. Where the cement or concrete is at all porous, the pitch layer renders it impervious to both gases and liquids. I

I claim:

The method of making a molded conduit, which consists in, first, producing aspiral metal core; second, covering said core with flexible material; third, applying to said cover a coating of adhesive material; fourth. forming upon said coated core the conduit body'of plastic material and allowing the same to harden, and fifth, withdrawing said spiral core.

' In testimony whereof I have a-flixed my signature in presence of two witnesses.

THOMAS E. MURRAY.

Witnesses:

GERTRUDE T. PORTER, MAY T. MGGARRY. 

